Paper cups are disposable cups that are manufactured from paper or paperboard. The paperboard is usually coated with a layer of polymer, wax or clay on one or either sides to make the cup water-proof. Paper cups are widely used in the food service industry.
Paper cups are meant for single use, after which they are disposed. Depending on the coating, a paper cup can be recycled. For example, cups that are lined with PLA can be fully composted, whereas PE-lined cups should be taken to landfill or incinerated.
Paper cups are often provided with a separate lid for rendering the cup spill-proof. Traditionally, the lids have been manufactured from plastic materials. Most lid models have an opening for a straw or a narrower opening for drinking directly. A major disadvantage of plastic lids is that they must be recycled separately from the paper cup which is made of paperboard.
An additional difficulty relates to the practical use of plastic lids. To close the lid in a liquid-tight manner requires that a user accurately exerts a certain amount of force to the lid edges so that the entire circumference of the lid becomes properly pushed down. If not, spilling may occur during walking due to sloshing of the liquid, or during drinking.
Various solutions have been put forward to develop an improved lid mechanism and to integrate a lid to a paper cup so that both the lid and the cup are made of the same material.
GB 2380397 A discloses a cup with two closure flaps formed integrally with the sidewall of the cup. To close the lid, the flaps are folded inwards to partly overlap each other.
US 2010/314434 A1 also describes a lid mechanism based on two opposing flaps that are integrated to the sidewall of the cup. To close the lid, the flaps are folded inwards to overlap each other entirely. One of the flaps has a tab with adhesive to keep the lid closed.
US 2014/042217 A1 describes a simple lid mechanism comprising two identical flaps that are folded on top of each other.
US 2002/0052286 A1 discloses a one-lid mechanism in which the lid is larger than the cross-section of the main body of the cup. The lid is pushed to some extent inside the body to seal it against the inner surface of the sidewall.
At least some embodiments of the present invention are intended to overcome the above discussed drawbacks and restrictions of the known paper cups and their lids.